The disclosure relates to a thermoplastic composition comprising polycarbonate polymers. The thermoplastic composition is translucent and has excellent physical properties. The thermoplastic composition comprises a matrix of a polycarbonate polymer in which are embedded polysiloxane domains.
Polycarbonate polymers are transparent engineering thermoplastic materials that combine desirable mechanical, optical, thermal, and electrical properties. Frequently polycarbonate polymers are blended with other materials to improve some mechanical properties such as impact resistance. The resulting blend typically exhibits reduced transparency or even opacity when compared to polycarbonate. In fact, transparency can be lost upon the addition of even small amounts of rubbery impact modifier. There is a growing need for translucent materials. Translucency occupies the middle ground between transparency and opacity, and is generally characterized by a combination of light transmission and haze. Currently available polycarbonate materials typically exhibit a certain level of translucency or opacity which cannot be manipulated over a visually significant range, without a significant variation in composition and physical properties.
There is an unprecedented demand for plastics having unique colors and looks. For example, cellular telephones having interchangeable plastic covers are now commonly available. These covers come in a variety of colors and/or special effects, giving consumers control over the aesthetic design of their phones. Many other injection molded plastic products used in applications such as, for example, computers, laptops, stereos and other consumer and/or business equipment, automotive interiors, etc., would also benefit from having unique colors and looks. Color and a variety of aesthetic effects such as sparkle, glitter, metal-like look, true metal appearance and other angular metameric effects are produced in thermoplastic compositions through the use of visual effect additives. Manipulation or fine tuning the color depth or visual effect requires control of the translucency of the polymer matrix.
The incorporation of visual effect additives can have a significant impact on a number of aesthetic and physical properties. The inclusion of visual effects additives can often decrease the impact strength of the material. Additionally, the incorporation of visual effect additives can result in visible flowlines, knitlines or weldlines in the finished product. Such flowlines, knitlines or weldlines can produce unattractive streaks in the product.
There remains a need for a thermoplastic composition with variable translucency that has excellent physical properties even in the presence of visual effects additives, especially at low temperatures.